全文获取类型
收费全文 | 892篇 |
免费 | 26篇 |
国内免费 | 13篇 |
专业分类
化学 | 501篇 |
晶体学 | 1篇 |
力学 | 26篇 |
数学 | 192篇 |
物理学 | 211篇 |
出版年
2020年 | 12篇 |
2019年 | 12篇 |
2016年 | 21篇 |
2015年 | 17篇 |
2014年 | 17篇 |
2013年 | 33篇 |
2012年 | 33篇 |
2011年 | 51篇 |
2010年 | 13篇 |
2009年 | 12篇 |
2008年 | 34篇 |
2007年 | 32篇 |
2006年 | 43篇 |
2005年 | 40篇 |
2004年 | 38篇 |
2003年 | 33篇 |
2002年 | 36篇 |
2001年 | 25篇 |
2000年 | 25篇 |
1999年 | 10篇 |
1998年 | 11篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 12篇 |
1994年 | 7篇 |
1993年 | 13篇 |
1992年 | 8篇 |
1991年 | 10篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 14篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 14篇 |
1984年 | 11篇 |
1983年 | 11篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1976年 | 16篇 |
1975年 | 17篇 |
1974年 | 7篇 |
1973年 | 8篇 |
1972年 | 7篇 |
1971年 | 6篇 |
1968年 | 6篇 |
1967年 | 5篇 |
排序方式: 共有931条查询结果,搜索用时 46 毫秒
71.
72.
Bioelectronics is a rapidly progressing interdisciplinary research field that has important implications for the development of biosensors, biofuel cells, biomaterial-based computers, and bioelectronic devices. Magneto-controlled molecular electronics and bioelectronics are new topics that examine the effect of an external magnetic field on electrocatalytic and bioelectrocatalytic processes of functionalized magnetic particles associated with electrodes. In this article we describe the progress in the developments of magneto-switchable electrocatalytic and bioelectrocatalytic transformations, and the effects of the rotation of the magnetic particles on the electrocatalytic and bioelectrocatalytic processes are discussed. Finally, the implications of the results on the development of biosensors, amplified immunosensors, and DNA sensors are described. 相似文献
73.
74.
Wallace Feurzeig Gabriel Katz Philip Lewis Victor Steinbok 《International Journal of Computers for Mathematical Learning》2000,5(3):283-284
Volume Contents
Volume Contents 相似文献75.
Mikhail Katz 《Israel Journal of Mathematics》2008,164(1):381-395
We show that the existence of a nontrivial Massey product in the cohomology ring H* (X) imposes global constraints upon the Riemannian geometry of a manifold X. Namely, we exhibit a suitable systolic inequality, associated to such a product. This generalizes an inequality proved in
collaboration with Y. Rudyak, in the case when X has unit Betti numbers, and realizes the next step in M. Gromov’s program for obtaining geometric inequalities associated
with nontrivial Massey products. The inequality is a volume lower bound, and depends on the metric via a suitable isoperimetric
quotient. The proof relies upon W. Banaszczyk’s upper bound for the successive minima of a pair of dual lattices. Such an
upper bound is applied to the integral lattices in homology and cohomology of X. The possibility of applying such upper bounds to obtain volume lower bounds was first exploited in joint work with V. Bangert.
The latter work deduced systolic inequalities from nontrivial cup-product relations, whose role here is played by Massey products.
Supported by the Israel Science Foundation (grants no. 620/00, 84/03, and 1294/06) 相似文献
76.
E Elhanany R Barak M Fisher D Kobiler Z Altboum 《Rapid communications in mass spectrometry : RCM》2001,15(22):2110-2116
Analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was applied for the characterization of Bacillus anthracis spore biomarkers. B. anthracis spores were extracted under a simple procedure, followed by linear mode analysis, using sinapinic acid as the matrix. Several markers with a mass range of 4-7 kDa were detected in three B. anthracis strains: Vollum, Sterne and V770-NP1-R. Similar spectra were also obtained for spore extracts of two members of the B. cereus group: B. thuringiensis and B. cereus, but not for B. mycoides, B. subtilis or B. licheniformis, suggesting that these markers are specific to closely related members of the B. cereus group. When alpha-cyano-4-hydroxycinnamic acid was used as the matrix, at least four additional new markers within a mass range of 2-4 kDa could be detected in all B. anthracis spore extracts. These markers, corresponding to a molecular weight of 2528.3, 2792.4, 3077.4, and 3590.7 Da, have not been observed in extracts of the three closely related Bacillus species - B. cereus, B. thuringiensis and B. mycoides. These unique B. anthracis biomarkers, which were isotopically resolved and reproducibly detected in the highly accurate MALDI-TOFMS reflectron mode, may be useful as a basis for rapid and specific identification of B. anthracis strains. 相似文献
77.
78.
We present several efficient dynamic data structures for point-enclosure queries, involving convex fat objects in
or
. Our planar structures are actually fitted for a more general class of objects – (β,δ)-covered objects – which are not necessarily convex, see definition below. These structures are more efficient than alternative known structures, because they exploit the fatness of the objects. We then apply these structures to obtain efficient solutions to two problems: (i) finding a perfect containment matching between a set of points and a set of convex fat objects, and (ii) finding a piercing set for a collection of convex fat objects, whose size is optimal up to some constant factor. 相似文献
79.
80.
We determine the smallest number f(n,k) such that every (0,1)-matrix of order n what zero main diagonal which has at least f(n,k) 1's contains an irreducible, principal submatrix of order K. We characterize those matrices with f(n,k)-1 l's having no irreducible, principal submatrix of order k 相似文献